This disambiguation page lists articles associated with the title UPD. If an internal link led you here, you may wish to change the link to point directly to the intended article.
Chronic smokers often have difficulty breathing because they develop Chronic Obstructive Pulmonary Disorder, or COPD. The two diseases that fall under that category are emphys â¦ ema and chronic bronchitis.
1 COPD (chronic obstructive pulmonary disease) is the term used for a group of diseases that cause difficulty exhaling and other symptoms, such as wheezing, a constant cough, and chest tightness. 2  Emphysema, often caused by years of smoking, is in this category of diseases.